III

ABSORPTION STUDY OF BIS PHENOL A USING

MOLECULAR IMPRINTED MEMBRANE

SITI FAIRUN ANNISHA BINTI HASSAN

Thesis submitted in partial fulfilment of the requirements

for the award of the degree of

Bachelor of Chemical Engineering (Biotechnology)

Faculty of Chemical & Natural Resources Engineering

UNIVERSITI MALAYSIA PAHANG

JUNE 2013

©SITI FAIRUN ANNISHA BINTI HASSAN (2013)

VIII

ABSTRACT

Endocrine disruptors component (EDCs) are environmental chemicals that affect the

function of the endocrine system, the system relating the glands and hormones of the

body. In this study, Bisphenol A (BPA) has selected for evaluation because it has

acknowledged significant consideration in recent years due to widespread human

exposures and concern for reproductive and developmental effects toward health. There

is some evidence that endocrine disruptors may not only impact the individual directly

exposed, but also future generations. So, the removal of BPA must be efficient to

protect our new generation and environment. In this study, Molecular Imprinted

polymer (MIP) has been chosen because of their advantages such as MIPs possess

excellent selective adsorption for templates due to the stereoscopic shape of specific

cavity and interactions. Thus, this research is aims to practice the removal of BPA from

aqueous solution by adsorption using an effective, reusable and low cost method like

molecular Imprinted membrane that have highly selective factor. The MIP was

synthesis by using bulk polymerization process and imprinted membrane were prepared

by using phase inversion method. The adsorption kinetics was studied by stirring BPA-

MIP, NIM and BPA-MIM in BPA aqueous solution for different times. The adsorption

isotherms were studied by stirring BPA-MIP, NIM and BPA-MIM in BPA solution at

different concentration. The maximum adsorption capacity of BPA ions for the NIM,

BPA-MIM, and BPA-MIP was 0.1268 mmol/g, 0.1328 mmol/g, 0.1149 mmol/g

respectively. In this study, it can be conclude that the MIP in membrane can absorb the

BPA more than BPA-MIP powder, and membrane alone.

IX

ABSTRAK

Komponen pengacau Endokrin (EDCs) adalah bahan kimia alam sekitar yang memberi

kesan kepada fungsi sistem endokrin, sistem yang berhubungan kelenjar dan hormon

badan. Dalam kajian ini, BPA telah dipilih untuk penilaian kerana ia telah diakui

terdapat peningkatan yang ketara dan pendedahan yang meluas terhadap manusia dan

alam sekitar dalam tahun-tahun kebelakangan dan terdapat kebimbangan untuk kesan

pembiakan dan pembangunan ke arah kesihatan. Terdapat beberapa bukti bahawa EDCs

bukan sahaja boleh memberi kesan kepada individu yang terdedah secara langsung,

tetapi juga generasi akan datang. Jadi, penyingkiran BPA perlu cekap untuk melindungi

generasi baru akan dating dan alam sekitar. Dalam kajian ini, polymer molecul bercetak

(MIP) telah dipilih kerana MIP mempunyai penjerapan terpilih yang cekap kerana

bentuk stereoskopik rongga dan interaksi tertentu. Oleh itu, kajian ini bertujuan untuk

menyerap BPA ion daripada BPA larutan akueus oleh penjerapan menggunakan,

kaedah kos rendah yang boleh diguna semula dan berkesan seperti membran dicetak

molekul yang mempunyai faktor yang sangat selektif. MIP disintesis menggunakan

proses pempolimeran pukal dan membran dicetak dengan menggunakan kaedah

penyongsangan fasa. Kajian mengenai kinetik penjerapan terhadap membrane, BPA-

MIP dan BPA-MIM dilakukan dalam masa yang berlainan untuk 24 jam. Kajian

mengenai isotermal penjerapan dilakukan terhadap membrane BPA-MIP, dan BPA-

MIM dalam larutan BPA pada kepekatan yang berbeza. Keupayaan penjerapan

maksimum ion BPA untuk membran , BPA-MIM, dan BPA-MIP adalah 0.1268

mmol/g, 0.1328 mmol/g, 0.1149 mmol/g masing-masing. Dalam kajian ini, ia boleh

membuat kesimpulan bahawa MIP dalam membran boleh menyerap lebih banyak BPA

daripada serbuk BPA-MIP, dan membran sahaja.

X

TABLE OF CONTENTS

SUPERVISOR‘S DECLARATION ............................................................................... IV

STUDENT‘S DECLARATION ...................................................................................... V

Dedication ....................................................................................................................... VI

ACKNOWLEDGEMENT ............................................................................................. VII

ABSTRACT ................................................................................................................. VIII

ABSTRAK ...................................................................................................................... IX

TABLE OF CONTENTS ................................................................................................. X

LIST OF FIGURES ........................................................................................................ XI

LIST OF TABLES ......................................................................................................... XII

LIST OF ABBREVIATIONS ........................................................................................ XII

1 INTRODUCTION .................................................................................................... 1

1.1 Motivation and statement of problem ................................................................ 1

1.2 Objectives ........................................................................................................... 1

1.3 Scope of this research ......................................................................................... 2

1.4 Main contribution of this work .......................................................................... 3

1.5 Organisation of this thesis ............................................................................... 3-4

2 LITERATURE REVIEW ......................................................................................... 5

2.1 Overview ............................................................................................................ 5

2.2 Introduction.........................................................................................................5

2.3 Previous work on BPA-MIP .............................................................................. 6

2.4 Evaluation of the BPA-MIP Using Adsorption Models .................................... 8 2.5 Review of MIM.................................................................................................10 2.6 Summary .......................................................................................................... 11

3 MATERIALS AND METHODS ............................................................................ 12

3.1 Overview .......................................................................................................... 12

3.2 Chemicals and Equipment................................................................................ 13

3.3 Synthesis of BPA-MIP and BPA-MIM............................................................ 14

3.4 Kinetic and Adsorption Isotherm study .......................................................... 15

3.5 Summary .......................................................................................................... 17

4 ADSORPTION STUDIES of BPA-MIP AND BPA-MIM .................................... 18

4.1 Overview .......................................................................................................... 18

4.2 Characterization of BPA-MIP and BPA-MIM.................................................18

4.3 Kinetic and Adsorption Isotherm Studies ........................................................ 20

4.4 Summary .......................................................................................................... 26

6 CONCLUSION ....................................................................................................... 27

6.1 Conclusion........................................................................................................ 27

6.2 Future work ...................................................................................................... 28

REFRENCES .................................................................................................................. 29

APPENDICES ................................................................................................................ 32

XI

LIST OF FIGURES

Figure 2-1: Schematic representation of covalent and non-covalent molecular imprinting

procedures. ........................................................................................................... 8

Figure 3-1: Overview of methodology ................................................................... 12

Figure 3-2: Formation of MIP copolymer ............................................................... 15

Figure 4-1: SEM images of MIP particles at 10 kV ................................................. 19

Figure 4-2: FT-IR spectra of (a) BPA, (b) BADM, (c) P(BADM-co-TRIM)H, (d)

P(BADM-co-TRIM)B by KBr pellet method .................................................................. 20

Figure 4-3: Binding Capacity of BPA (umol BPA/mg Polymer) at different time in 0.13

umol/ml BPA solution, 150 rpm and temperature, 25ᵒC.................................................22

Figure 4-4: Binding Capacity of Polymer (umol BPA/mg Polymer) at different

concentration at 90 minutes, 150 rpm and temperature, 25oC ........................................ 23

Figure 4-5: Binding performances of MIP in 0.13 mmol/L BPA solution, 150 rpm and

temperature, 25ᵒC................................................................................................. 24

Figure 4-6: Maximum binding capacity of Polymer (umol BPA/mg Polymer) at 16 hour,

in 0.13 mmol/L BPA solution, 150 rpm and temperature, 25oC ................................. 25

XII

LIST OF TABLES

Table 3-1: List of equipment used .................................................................................. 13

Table 3-2: List of chemical used ..................................................................................... 13

Table 4-1: Binding Capacity of Polymer (mmol BPA/g Polymer) at different time

(h).....................................................................................................................................21

Table 4-2: Binding Capacity of Polymer (mmol BPA/g Polymer) at different

concentration (umol/mL). ............................................................................................... 22

XIII

LIST OF ABBREVIATIONS

ED Endocrine Disruptor

EDC Endocrine Disruptor Component

BPA Bis Phenol A

WW Waste Water

WWS Waste Water Sludge

MIP Molecular Imprinted Polymer (In powder form)

BPA-MIP Molecular Imprinted Polymer with BPA template (In powder form)

MIM Molecular Imprinted Membrane

BPA-MIM Molecular Imprinted Membrane with BPA template

NIP Non Imprinted Membrane

SEM Scanning electron microscope

FTIR Fourier Transform Infrared

IR Infrared

BADM Bisphenol A dimethacrylate

NMP N-methyl pyrorolidone

THF Tetrahydofuron

AIBN Azobibidobutyronitrile

TRIM Trimehylolpropane trimethacrylate

Psf Polysulfone

ACN Acetonenitrile

1

1 INTRODUCTION

1.1 Motivation and statement of problem

Endocrine disruptors (EDs) are environmental chemicals that affect the function of the

endocrine system, the system relating the glands and hormones of the body. The

endocrine system coordinates the functions of various organs and systems in the body.

EDs may interrupt the endocrine system in some ways: they may act as "imposters" of

naturally occurring hormones, block the action of hormones, modify the chemical

message sent by hormones, and disrupt the production of hormones or hormone

receptors (Vanderberg et al., 2007).

Most EDs act like naturally occurring estrogens in the body. The theory of endocrine

disruptors gained credibility from a number of studies demonstrating reproductive

problems in wildlife exposed to certain environmental chemicals. EDs are a different

class of chemicals. They include: certain pesticides, industrial chemicals like PCBs, and

dioxins, phthalates, phenols like bisphenol A, and alkylphenol, and plant hormones like

phytoestrogens (Vanderberg et al., 2007).Endocrine disrupting compounds (EDCs) have

caused various adverse health effects which have been reported in recent years. The

EDCs has been as a social, environmental and global issue (Mohapatra et al., 2010).

Due to this, an effective treatment and disposal of Bisphenol A (BPA) in waste water

(WW) or waste water sewage (WWS) has been one of the major concerns in wastewater

treatment processes to degrade organic pollutants including BPA. There are several

kinds of pre-treatment methods studied so far which involve chemical treatment,

mechanical treatment, oxidative treatment, biological hydrolysis or combination of any

two of these methods. One of the latest technologies in BPA extraction is using

molecular recognition (Kryscio and Peppas., 2012).

Molecular recognition is a fundamental biological mechanism ubiquitous in nature. This

elegant, yet simple, mechanism is found in a variety of biological processes, including

antibody/antigen recognition in the immune system, enzymatic catalysis, signal

transduction, and nucleic acid interactions such as replication, transcription, and

translation. Molecular imprinting is a promising field in which a polymer network is

2

formed with specific recognition for a desired template molecule. This technique has

been successfully applied to small molecule templates in the areas of separations,

artificial enzymes, chemical sensors, and pharmaceuticals which will be discussed on

chapter 2 .The imprinting of small molecules is well developed, and tailor-made

molecular imprints are now available commercially (Mohapatra et al., 2010).

According to the Toxics Release Inventory database, total environmental release of

bisphenol A in 2004 was 181,768 pounds, with releases of 132,256 pounds to air, 3533

pounds to water, 172 pounds to underground injection, and 45,807 pounds to land.

There is extensive evidence that many consumer products contain and release BPA and

many of these products leach BPA under normal conditions of use. BPA has been

detected in baby bottles, epoxy resins, and other consumer plastics and also been

detected in a wide range of foods stored in cans with epoxy resins. There is very good

evidence to indicate that BPA can be detected in environmental samples, including air,

dust and water. Evidence for this is supported by studies of landfill leachates which

indicate substantial release of BPA from landfills (Vandenberg et al., 2007). Hence, the

detection of BPA is very important in maintaining an awareness of pollutants in our

immediate environments. Recently, various methods have been employed for the

determination of BPA. Most use methods are adsorption method using activated carbon

or clay as absorber. However, these methods are expensive, and require pre-treatment.

In this study, MIP has been chosen because of their advantages such as MIPs possess

excellent selective adsorption for templates due to the stereoscopic shape of specific

cavity and interactions. In addition to this property, they are reusable and durable

against chemical conditions.

1.2 Objectives

The aims of this research are to study the adsorption of BPA-MIM toward BPA.

3

1.3 Scope of this research

The following are the scope of this research:

i) The synthesis of MIM

ii) To study the characterization of BPA-MIP and BPA-MIM

iii) To study the adsorption/absorption performance of BPA-MIP and BPA-

MIM towards BPA.

1.4 Main contribution of this work

In this study, BPA has selected for evaluation because it has acknowledged significant

consideration in recent years due to widespread human exposures and concern for

reproductive and developmental effects toward health. BPA is most commonly

described as being ―weakly‖ estrogenic; however, an emerging body of molecular and

cellular studies indicate the potential for a number of additional biological activities

(Shelby. M. D., 2007). There is some evidence that endocrine disruptors may not only

impact the individual directly exposed, but also future generations. So, the removal of

BPA must be efficient to protect our new generation and environment.

1.5 Organisation of this thesis

The structure of the reminder of the thesis is outlined as follow:

Chapter 2 provides a description of the applications and general design features of

imprinted polymer. General description BPA properties are presented. This chapter also

provides a brief discussion of the advanced experimental techniques available for MIP

and MIM synthesis and mentioning their applications. A summary of the previous

experimental work on MIP is also presented.

Chapter 3 gives a review of the approach applied for synthesis of BPA-MIM and BPA-

MIP and experimental procedures. The performances of three different polymers, the

imprinted powder, imprinted membrane and NIM were compared with batch binding

capacity experimental data.

Chapter 4 is devoted to discuss on the results of the experiment that was done in order

to determine which Polymer between BPA-MIP, BPA-MIM and NIM is more effective

in absorption process in term of binding capacity of BPA in mg Polymer. The

4

characterization of BPA-MIP and BPA-MIM using SEM and FTIR is also presented, a

brief review of the kinetic and adsorption isotherm result is also outlined.

Chapter 5 draws together a summary of the thesis and outlines the future work which

might be derived from the model developed in this work.

5

2 LITERATURE REVIEW

2.1 Overview

A literature review was introduced to classified studies that related to the topic. There

are five theme in this literature review which is overview of BPA include characteristic

of BPA, sources of BPA, and effect of BPA towards our health. This chapter also

provide overview of Molecular imprinted polymer (MIP), which is the special

molecular recognition effecting factors like monomer, template, cross linking and etc,

preparation method of MIP and adsorption isotherms.

2.2 Introduction

Endocrine disruptors are naturally occurring compounds or human made chemicals that

may obstruct with the production or activity of hormones of the endocrine system

leading to undesirable health effects. Several of these chemicals have been connected

with developmental, neural, reproductive, immune, and other problems in flora and

fauna and laboratory animals. A few scientists think these chemicals also are adversely

affecting human health in similar ways resulting in declined fertility and increased

incidences or progression of some diseases including endometriosis and cancers

(Endocrine disruptors., 2007)

Endocrine disruptors can mimic or partly mimic naturally taking place hormones in the

body like estrogens (the female sex hormone) and androgens (the male sex hormone)

and thyroid hormones, potentially producing overstimulation. It also can attach to a

receptor contained by a cell and block the endogenous hormone from binding. The

typical signal then fails to occur and the body fails to respond properly. Examples of

chemicals that block or antagonize hormones are anti-estrogens or anti-androgens. The

ED also can interfere or block the way natural hormones or their receptors are made or

controlled, for example by blocking their metabolism in the liver (Endocrine disruptors.,

2007). Chemicals that are known endocrine disruptors include diethylstilbestrol (the

drug DES), dioxin and dioxin like compounds, PCBs, DDT, and some other pesticides.

This study pays more attention to BPA because of its widely application in industry.

6

2.3 Previous work on BPA-MIP

In the past few years molecular imprinting has entered many areas of chemistry,

biochemistry and biotechnology. Nowadays polymers imprinted with different

templates like drugs, herbicides, sugars, nucleotides, amino acids and proteins are more

and more applied in analytics, as well as in catalysis or for synthetic processes (Huang

et al., 2012).

Molecular imprinting technology plays an important role in constructing molecule

recognition sites into some polymer matrix (Zhao et al., 2008). The current opinion

about molecular imprinting is a technology in which specific recognition sites are

formed in a polymer matrix by synthesis in the presence of the template molecule, or

‗imprinting‘ molecule which results in the formation of specific recognition cavities

complementary to the template in shape and chemical functionality (Yang et al,. 2005).

Molecular imprinting is a method for producing chemically selective binding sites,

which distinguish a particular molecule, in a macro porous polymer matrix (Mayes &

Mosbach., 1997). The current opinion about the MIP is that their peculiar molecular

recognition properties are due to the presence of nanocavities formed during a

polymerization process developed in the presence of a template molecule and of suitable

functional monomers. According to the key-lock principle by Kryscio and Peppas,

(2012); the shape of the nanocavities is complementary to that of the template. The non-

covalent interactions which govern the molecular recognition mechanism are

established between the binding site and a single, isolated template molecule.).

Extraction of the template leaves sites in the polymer with specific shape and functional

group complementarily to the original template (Zhang et al., 2009). Moreover, as

regards a polymer obtained by the non-covalent imprinting technique, the key-lock

principle should be intended as effectively operating not in materials possessing a

single, well-defined class of binding site but in a complex environment constituted by a

multiplicity of binding sites with a wide and perhaps continuous distribution of

affinities for the template (Bagiani et al., 2004).

Intermolecular forces that develop during polymerization between the template

molecules (T), functional monomer (M) and developing polymer matrix are responsible

for creating a polymer microenvironment for the template or imprint molecule. The

7

process called imprinting polymerization consists of polymerizing a functional

monomer, mixed with a template, in the presence of a very big portion of cross-linker.

After the pre-arrangement between functional monomers and the template, the template-

functional monomers and cross-linkers are co-polymerized. The extraction of template

from Imprinted binding site is done by extensive washing using solvent. Thus, the

binding sites are left, which are complementary to the template in size, shape, and

functional groups (Batra and Shea., 2003).

Many variables of the imprinting process influence the selectivity and capacity of a

MIP. First, complementary interactions between the template and the functional a cross

linking monomers are necessary to create short-range molecular organization at the

receptor site in presence of a initiator. These interactions include hydrogen bonding,

electrostatic and/or van der Waals forces. Second, the stoichiometry and concentration

of the template and monomers influences both polymer morphology and MIP

selectivity. Third, the solvent used in the polymerization process and finally, the

temperature of polymerization influences the timing of phase separation. Also, the

temperature dependence of the equilibrium between the functional monomers and

template affects MIP selectivity and capacity (Batra and Shea., 2003).

Basically, two types of molecular imprinting strategies have been established based on

covalent bonds or non-covalent interactions between the template and functional

monomers as shown in Figure 2.1. In both cases, the functional monomers, chosen so as

to allow interactions with the functional groups of the imprinted molecule, are

polymerized in the existence of the imprinted molecule. The special binding sites are

formed by covalent or, more commonly, non-covalent interaction between the

functional group of imprint template and the monomer, followed by a cross linked co-

polymerization (Takeda & Kobayashi., 2005).

During the non-covalent approach, the special binding sites are formed by the self-

assembly between the template and monomer, followed by a crosslinked co-

polymerization (Svenson et al., 2004 & Ekberg and Mosbach., 1989). The imprint

molecules interact, during both the imprinting procedure and the rebinding, with the

polymer via non-covalent interactions, like ionic, hydrophobic and hydrogen bonding.

The non-covalent imprinting approach seems to hold more potential for the future of

8

molecular imprinting due to the vast number of compounds, including biological

compounds, which are capable of non-covalent interactions with functional monomers

(Sellergen et al., 1993 & Michael et al., 1997)

Figure 2-1: Schematic representation of covalent and non-covalent molecular imprinting

procedures.

2.4 Evaluation of the BPA-MIP Using Adsorption Models

The discrete Langmuir and bi-Langmuir models are mostly simple to implement via

Scatchard plots and generate the corresponding binding parameters: binding affinity (K)

and number of binding sites (N). In the Scatchard analysis, the experimental binding

isotherm is plotted in q/C versus q format (where q is the concentration of the analyte

bound to a polymer in mol g−1 and C is the concentration of free analyte remaining in

the solution in mol L−1). In homogeneous systems that contain only one type of binding

site, the Satchard plot falls on a straight line with a slope equal to the negative of the

9

binding affinity (−K) and an x-intercept equal to the number of binding sites (N) as

show in equation 2.1.

q/C = KN − Kq (2.1)

In contrast, the Scatchard plots for most MIPs are curved. This curvature has been cited

as evidence for binding site heterogeneity. Heterogeneity can still be accommodated

using the Scatchard analysis by modelling the curved isotherm as two separate straight

lines (bi-Langmuir model). This limiting slopes method yields two separate sets of

binding parameters (K1, N1 and K2, N2) for two classes of sites. To predict the

favourability of the adsorption system, the Langmuir equation may also be expressed in

terms of a dimensionless separation factor RL defined as equation 2.2 where C0 is the

initial BPA concentration (mol L−1

) and K is the Langmuir adsorption equilibrium

constant (L mol−1

). The parameter RL > 1, RL = 1, 0 < RL < 1, RL = 0, indicates the

isotherm shape according to unfavourable, linear, favourable and irreversible,

respectively (Pereza et al., 2011 & Zakaria. et al., 2009).

𝑅𝐿 = 1/(1 + KC0) (2.2)

Zakaria et al., 2009 have studies the adsorption of 2,4-dinitrophenol by MIP. According

to the study, the equation is frequently used in the linear form by taking the logarithm of

both sides as:

Log qe = log Kf +1/ n log Ce (2.3)

Where Kf and n are isotherm constant, respectively. The applicability of the Freundlich

sorption is also analyzed by plotting log qe versus log Ce. To determine the constant Kf

and n, the linear form of equation, Eq 2.3 can be used. Compared to Freudlich, the

Langmuir plots have a higher correlation coefficient of 0.985. It can be confirmed that

2,4-dinitrophenol adsorption by MIP follow the Langmuir (Yusof et al., 2010 & Yusof

et al., 2009).

10

2.5 Review on MIP Membrane

A membrane is an interphase involving two adjacent phases acting as a selective barrier,

at the mean time organizes a system into compartments and regulating the transport

between the two compartments. The most important advantages of membrane

technology as compared with other unit operations in biochemical engineering are

associated to the unique separation principle, like the transport selectivity of the

membrane. In addition, separations with membranes do not require additives, and they

can be performed isothermally and at very competitive energy consumption (Ulbricht.,

2004). Membrane technology has been already applied in many industrial fields like

food, energy, environment, and artificial organs but, the possibility to introduce specific

recognition sites in a synthetic membrane plays an important role for the transport of

specific substances. An imprinted membrane is able to discriminate between target

molecules and others, thus improving the separation process (Tasselli et al., 2008).

To develop molecularly imprinted membranes, which have become a latest category of

membrane-absorbent materials, various challenges have acknowledged much attention

and certain successes have been achieved. A MIM is a membrane either composed of a

MIP or containing a MIP (Ulbricht., 2004 and Son et al., 2011). A high membrane

performance depends on well-defined membrane morphology with respect to barrier

pore size and layer topology, especially the thickness of the barrier layer (Ulbricht.,

2004). First studies on molecularly imprinted polymer membranes were performed by

Piletsky et al., in 1999 via in situ bulk polymerization of acrylate monomers. Since

then, further researchers prepared successfully imprinted membranes using the similar

method and try to approach another method (Tasselli., 2008). Dry phase separation, wet

phase inversion, and surface imprinting have been investigated as possible methods to

prepare imprinted membranes. In 1996, Kobayashi and friends have developed a

method to prepare imprinted membranes, through phase inversion via non-solvent

induced phase separation from a viscous solution of the membrane-forming polymer

and the imprinted molecule. The washing of the membrane leaves in the structure free

cavities that are able to bind the print molecule better than nonimprinted membrane and

selectively with respect to molecules of similar structure as, theophylline with respect to

caffeine (Silvestri et al., 2006).

11

In the first work on that MIM preparation, Ulbricht., (2004) had used polystyrene resins

with peptide recognition groups, in a blend with a matrix polymer, for the MIM

formation via a ―dry PI‖ process, the polymer solidification was achieved by solvent

evaporation. Remarkably, the permeability was much higher for the MIM as compared

with the blank membranes. On the other hand, Takeda and Kobayashi., (2005) had used

functional acrylate copolymers for a ―wet PI‖ process yielding asymmetric porous

MIM. In that case, the polymer solidification was achieved through a precipitation

induced by contact with a non-solvent. The copolymer material and methodology had

recently successfully been adapted by another group. In the meantime, the polymer

selection for phase inversion imprinting had been extended to mainly of the frequently

used membrane materials, example cellulose acetate, polyamide, polyacrylonitrile and

polysulfone. The formation of porous MIM from a compatible blend of a matrix

polymer for adjusting a permanent pore structure and a functional polymer for

providing binding groups could provide even more alternatives. Furthermore,

polyethyleneglycol as pore former in the polymer blend casting solution had been

successfully used to increase the membrane permeability (Ulbricht., 2004).

It is remarkable, that most MIM prepared via phase inversion imprinting had at least

acceptable binding performance in aqueous media. However, such MIM lost their

―template memory‖ when exposed to a too organic environment where swelling and

chain rearrangement seemed to ―erase‖ the imprinted information .However, it should

be noted, that even if the phase inversion should be most suited for the preparation of

separation membranes, the adaptation of the process to the preparation of MIM is

complicated because the conditions required for an optimal formation of MIP sites may

not be compatible with the ones for obtaining an optimal pore structure (Ulbricht.,

2004).

2.6 Summary

This literature review is the information of mass transfer study of MIP on BPA removal.

MIP membrane has been chosen because of the highest selectivity and for the

preparation of MIP, bulk polymerization is chosen. This chapter also have discussed

about the adsorption isotherm and kinetics study about MIP.

12

3 MATERIALS AND METHODS

3.1 Overview

This section covers a method for BPA-MIP and BPA-MIM synthesis process. The

resultant polymer was used to study their characterization using FTIR and SEM. This

section provides scheme used in kinetic and adsorption study on BPA removal from

BPA aqueous solution. The absorption of BPA is study in term of binding capacity of

the BPA in polymer. Figure 3.1 summarizes the overview of this study.

Figure 3.1 Overview of methodology

13

3.2 Chemicals and Equipment

The chemicals and equipment used in this study is of analytical grades, and they are

summarizes in Table 3.1 and Table 3.2.

Table 3.1 List of equipment used

Equipment Brand Principal Used

Incubator Shaker BS-21 Experiment

UV-Vis Spectrophotometer U-1800 Analysis

FTIR Thermo Nicolet Characterization

SEM Zeiss Characterization

Table 3.2 List of chemical used

Chemical Principal used

Bis Phenol A (BPA) Analysis

Bisphenol A dimethacrylate (BADM) MIP synthesis

N-methyl pyrorolidone (NMP) MIM synthesis

Polysulfone MIM synthesis

Trimehylolpropane trimethacrylate (TRIM)

MIP synthesis

Acetonenitrile MIP synthesis

Azobibidobutyronitrile (AIBN) MIP synthesis

Tetrahydofuron (THF) Hydrolysis

Sodium Hydroxide(NaOH) Hydrolysis

14

3.3 Synthesis of BPA-MIP and BPA-MIM

Synthesis of MIP is done by using the Bulk polymerization process. The formulations

of BPA imprinted copolymer were showed in figure 3.2. The templates (BPA) were

mixed with the functional monomer (BADM), the cross-linker (TRIM) in 1:10 mol ratio

and ACN as a solvent. AIBN was applied as initiator of the polymerization solution.

The glass tube was sealed and placed under after purging with nitrogen gas for 5 min to

completely evacuate the air, thus avoiding the polymerization inhibition. Finally, the

polymerization was carried out at 80 ◦C for 12 h at 200 rpm.

Then, the resulting precipitate was centrifuged and the supernatant was filtered under

vacuum/was crushed with pestle and mortar. These copolymers were washed with ACN

and then in THF. Then the polymer obtained was dry in desiccators until the constant

weight obtained. Template removal was carried out via hydrolysis reaction in aqueous

solution containing 1M Sodium Hydroxide (NaOH) at 50 oC with agitation until BPA

concentration reached constant which the concentration reading were taken using UV-

Visible Spectrophotometer (UV-Vis). The hydrolyzed polymers were washed with

excess water until neutral pH.

Phase inversion techniques were selected in synthesis of BPA-MIM. Psf were used for

hybridization with BPA-MIP powder. Phase inversion process of the polymer and the

BPA-MIP powder was taken place as following. The BPA-MIP powder was mixed with

70% of NMP solution by stirring overnight at 50◦.C. The resultant viscous solution was

spread on glass plate with thickness controlled by polyester film used as spacer at

50◦C.Then spread polymer was immediately coagulated in 2L of water at 25

◦C and kept

overnight in order to remove the solvent. After solidification, the resultant membrane

was washed with excess of water. As references, membrane were prepared by similar

phase inversion phase but not adding the BPA-MIP powder.

The characterization of BPA-MIM and BPA-MIP were conducted using Scanning

electron microscope (SEM) and Fourier Transform Infrared (FTIR) Spectrometry. A

Scanning electron microscope (SEM) ZEISS EVO 50 with EDX was used for the

morphology observation of the BPA-MIM cross-sections. The FTIR Model Thermo

Nicolet spectra equipment was used to measure the IR spectra of MIP to confirm the

complete removal of BPA from the template.

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Figure 3.2: Formulation of BPA imprinted copolymer

3.4 Kinetic and Adsorption study

Batch binding tests were carried out to evaluate the binding properties of the BPA-MIP

and BPA-MIM. The rate of the adsorption of BPA by the BPA-MIP, BPA-MIM and

NIM from BPA aqueous solutions was investigated as a function of time. The

adsorption kinetics for BPA-MIP was studied by stirring BPA-MIP, NIM and BPA-

MIM (0.05 g) in 30 mg/ml BPA aqueous solution (50 mL) for different times in 24

hours. Immediately after mixing, the suspension was allowed to bind BPA by shaking at

150 rpm and 25oC. During this period samples were collected at fixed intervals times.

The adsorption isotherms were studied by stirring the polymer (0.05 g) in BPA aqueous

solution (50 mL) at different concentration from 0.09 mmol/L to 0.28 mmol/L. The

16

concentration of the BPA compounds after treatment was measured by UV-Vis

Spectroscopy at 276 nm.

The binding capacity was calculated as below:

𝑞 = 𝐶𝑂 − 𝐶𝑓 𝑉

𝑀

(3.1)

Where q (umol BPA/mg Polymer) is the amount of total adsorption of BPA, CO and CF

are initial and final concentration of BPA in solution (umol/mL), respectively. V is the

volume of the solution in mL and M is the weight of Polymer in mg.

During the batch experiments, adsorption isotherms were used to evaluate adsorption

properties. For the systems considered, the Langmuir model was found to be applicable

in interpreting BPA adsorption on the BPA imprinted polymer. The Langmuir isotherm

is based on the assumption that the solid surface presents a finite number of identical

sites which are energetically uniform, there is no interaction between sorbed species,

meaning that the amount of sorbate molecules sorbed has no influence on sorption rate;

and monolayer is formed when the solid surface reaches saturation.

The Langmuir model is probably the best known and most widely applied sorption

isotherm. It has produced good agreement with a wide variety of experiment data and

may be represented as follows (Liu et al. 2010):

𝑞𝑒 = 𝑞𝑚𝑏 𝐶𝑒

1 + 𝐶𝑒

(3.2)

The above equation can be rearranged to the following linear form

𝐶𝑒

𝑞𝑒=

𝐶𝑒

𝑞𝑒+

1

𝑏𝑞𝑚

(3.3)

Where Ce is the equilibrium concentration, qe the amount of BPA adsorbed at

equilibrium, qm is amount of BPA adsorbed for a complete monolayer, b is a constant

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related to the energy or net enthalpy of sorption. The sorption data were analysed using

the linear form Eq. (3.3) of the Langmuir isotherm.

3.5 Summary

This section consists of synthesizing of BPA-MIP and BPA-MIM technique. It also

covers the study of adsorption isotherm and kinetic study of adsorption of BPA-MIP

and BPA-MIM towards BPA solution. The resultant polymer was also characterized

using FTIR and SEM.